1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method. In particular, the invention relates to a semiconductor device manufacturing method wherein an insulating circuit substrate mounted with a semiconductor element is housed inside a resin case, and a terminal is integrally molded with the resin case.
2. Description of the Background Art
A semiconductor module wherein a plurality of power semiconductor elements, such as an insulated gate bipolar transistor (IGBT) or freewheeling diode (FWD) is housed inside a resin case is known as a semiconductor device that controls a motor or the like.
As one example of this semiconductor module, a power semiconductor element is mounted on an insulating circuit substrate. The insulating circuit substrate is formed such that an electrical circuit formed of a conductive layer is formed on a surface of an insulating substrate, and the power semiconductor element is electrically connected via a solder to the electrical circuit. The insulating circuit substrate mounted with the power semiconductor element is housed inside a resin case. A terminal is provided in the resin case. The conductive layer electrical circuit of the insulating circuit substrate, or the power semiconductor element, is electrically connected with a bonding wire to the terminal. The terminal can be electrically connected as a main terminal or control terminal to the exterior of the resin case. The insulating circuit substrate mounted with the power semiconductor element is joined to the resin case with an adhesive. A sealing resin is injected into the resin case, and prevents moisture and the like from entering the resin case, thus protecting the power semiconductor element and the like.
As one example, the terminal has an L-shape having a leg portion. As one example, the resin case has a box shape having a side wall portion provided on each of four sides. The L-shaped terminal is provided in the resin case so that a leading end portion of the terminal is exposed from an upper end of the side wall portion of the resin case, and the leg portion of the terminal is exposed on the inner surface side of the side wall portion of the resin case. The number and positions of terminals in the side wall portion of the resin case differ for each semiconductor module product.
As a method of manufacturing a resin case wherein terminals are provided integrally, there is the following method.
A terminal member wherein terminals are connected by tie bars for a number and position corresponding to one side wall portion of the resin case is prepared for each side wall of the resin case by carrying out a punching process and bending process on a thin plate of a conductive material, such as a copper plate. The terminal members are positioned to correspond to each of the side walls of the resin case in a molding die in which the resin case is to be molded, and the terminals are insert molded integrally with the resin case by a raw material resin such as a polyphenylene sulfide (PPS) resin being injected into the molding die and hardened. After molding, the tie bar is cut off.
However, while this method is suited for mass production, the terminal member is arranged to have a structure wherein the terminals are connected by the tie bar so as to be in predetermined positions, so that unnecessary portions between terminals are thrown away in the punching process. Consequently, the proportion of the portion of the thin plate of conductive material used for the terminals is low, and the terminal cost is high. Also, when manufacturing resin cases with differing terminal layouts, it is necessary to separately prepare different molding dies in accordance with the number and positions of the terminals, and the molding die cost is high because of the need to prepare a plurality of molding dies.
In, another method of manufacturing a resin case wherein terminals are provided integrally, terminal attachment holes are formed in a side wall portion of the resin case in the resin case molding step so as to be compatible with all terminal arrays differing in accordance with model and specifications, and individual terminals are press fitted in predetermined positions into the attachment holes formed (JP-A-2008-252055 (Description of the Background Art, Claims)).
With this method, one resin case molding die is sufficient even when manufacturing resin cases with differing terminal numbers and positions, and the molding die cost is lower than with the previously described method. Also, as it is sufficient that individual terminals of the same form are manufactured from a thin plate of a conductive material, the proportion of the portion of the thin plate of conductive material used for the terminals is high, and the terminal cost is lower than with the previously described method. Also, standardization is also possible for the resin case, and the member cost is therefore low. However, as an operation of fitting the terminals one by one into the terminal attachment holes is necessary for the number of terminals provided in the resin case, the operation cost is high. Also, as it is necessary to attach a terminal holding frame on the bottom surface of the side wall portion of the resin case after the press fitting of the terminals, and fix the terminal holding frame using an adhesive, in order to prevent looseness of the leg portion of the terminal and secure wire bondability, a terminal holding frame manufacturing cost and adhesive cost are incurred. Consequently, the overall cost reduction is insufficient.
In another method of manufacturing a resin case wherein terminals are provided integrally, protruding portions having elasticity are formed on an inner surface side of a side wall portion of the resin case, and terminals are clamped by the protruding portions (JP-A-2009-21286 (Claims)). With this method too, one resin case molding die is sufficient even when manufacturing resin cases with differing terminal numbers and positions, and the molding die cost is lower than with the previously described insert molding method. Also, as it is sufficient that individual terminals of the same form are manufactured from a thin plate of a conductive material, the proportion of the portion of the thin plate of conductive material used for the terminals is high, and the terminal cost is lower than with the previously described method. Also, standardization is also possible for the resin case, and the member cost is therefore low. However, as an operation of attaching the terminals one by one into the protrusions is necessary for the number of terminals provided in the resin case, the operation cost is high. Also, as it is necessary to fix a universal guide including the protrusions to the case using an adhesive, a universal guide manufacturing cost and adhesive cost are incurred. Consequently, the overall cost reduction is insufficient. Also, as it is necessary that the protruding portions of the resin case are formed of a material having elasticity, it is not possible to use a PPS resin or the like, which have low elasticity.
A semiconductor device wherein terminals of the same form are integrally molded in a side wall portion of a resin case using a molding die is described in JP-A-9-8223 (Paragraph [0117], FIG. 3) and JP-A-2004-134518 (Paragraph [0051]). However, it is not necessarily clear in JP-A-9-8223 (Paragraph [0117], FIG. 3) and JP-A-2004-134518 (Paragraph [0051]) whether the method described in JP-A-2008-252055 (Description of the Background Art, Claims) or the method described in JP-A-2009-21286 (Claims) is used as the method for molding the terminals integrally with the resin case.